<template>
  <div class="pdf-preview">
    <div
      id="page-view"
      :style="{
        position: 'absolute',
        top: '50%',
        left: '50%',
        transform: `translate(-50%, -50%) scale(${state.scale})`,
        width: '100%',
        height: `${pageHeight}`,
      }"
    >
      <vue-pdf-embed
        :source="state.source"
        :page="state.pageNum"
        textLayer
      />
    </div>
  </div>

  <div class="page-tool">
    <div class="page-tool-item" @click="lastPage">上一页</div>

    <div class="page-tool-item" @click="nextPage">下一页</div>

    <div class="page-tool-item">
      {{ state.pageNum }}/{{ state.numPages }}
    </div>

    <div class="page-tool-item" @click="pageZoomOut">放大</div>

    <div class="page-tool-item" @click="pageZoomIn">缩小</div>
  </div>
</template>

<script setup>
import { reactive, onMounted, ref } from "vue";

import VuePdfEmbed from "vue-pdf-embed"; 
import { createLoadingTask } from "vue3-pdfjs"; 

const props = defineProps({
  pdfUrl: {
    type: String, 
    required: true,
  },
});

const pageHeight = ref("100%");

const state = reactive({
  source: props.pdfUrl, //预览pdf文件地址

  pageNum: 1, //当前页面

  scale: 1, // 缩放比例

  numPages: 0, // 总页数
});

function lastPage() {
  if (state.pageNum > 1) {
    state.pageNum -= 1;
  }
}

function nextPage() {
  if (state.pageNum < state.numPages) {
    state.pageNum += 1;
  }
}

function pageZoomOut() {
  if (state.scale < 2) {
    state.scale += 0.1;

    pageHeight.value = parseInt(pageHeight.value) - 5.0 + "%";
  }
}

function pageZoomIn() {
  if (state.scale > 1) {
    state.scale -= 0.1;

    pageHeight.value = parseInt(pageHeight.value) + 5.0 + "%";
  }
}

onMounted(() => {
  const loadingTask = createLoadingTask(state.source);

  loadingTask.promise.then((pdf) => {
    state.numPages = pdf.numPages;
  });
});
</script>

<style lang="css" scoped>
.pdf-preview {
  position: relative;

  height: 100vh;

  padding: 20px 0;

  box-sizing: border-box;

  background-color: #e9e9e9;
  width: 300px
}

.pdf-wrap {
  overflow-y: auto;
}

.vue-pdf-embed {
  text-align: center;

  width: 515px;

  border: 1px solid #e5e5e5;

  margin: 0 auto;

  box-sizing: border-box;
}

.page-tool {
  position: absolute;

  bottom: 35px;

  padding-left: 15px;

  padding-right: 15px;

  display: flex;

  align-items: center;

  background: rgb(66, 66, 66);

  color: white;

  border-radius: 19px;

  z-index: 100;

  cursor: pointer;

  margin-left: 50%;

  transform: translateX(-50%);
}

.page-tool-item {
  padding: 8px 15px;

  padding-left: 10px;

  cursor: pointer;
}
</style>
